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Reflections on Moonsighting

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1 Reflections on Moonsighting
With the Name of Allah, All-Merciful, Most Merciful Reflections on Moonsighting Dr. Usama Hasan (Al-Tawhid Mosque & Royal Observatory Greenwich) presented at: The Mu’adh Centre, Birmingham to the Nigerian Muslim Federation 6th Jumada al-Ula 1430 / 2nd May 2009

2 Synopsis Ayat, Signs … Surah Names The Sun
The Moon & Crescent-Sighting issues Stars & Simulations

3 Ayat, Signs … “We have made the sky a protected ceiling;
But they are, about its Signs, unmindful.” “And amongst His Signs are the night and the day, The sun and the moon …”

4 Chapters of the Qur’an Al-Shams (The Sun) Al-Qamar (The Moon)
Al-Najm (The Star) Al-Buruj (The Constellations or Zodiacal Signs) Al-Tariq (The Piercing Star) Al-Fajr (Dawn) Al-Layl (Night) Al-Duha (The Forenoon) Al-’Asr (The Late Afternoon) Al-Falaq (Daybreak)

5 Earth’s Annual Motion: Seasons

6 Annual Motion of the Sun, Moon, Planets & Stars
“Lord of the Two Easts, Lord of the Two Wests! So which of the favours of your Lord will you deny?” (al-Rahman 55:17-18) “Lord of the East(s) and West(s) …” (Muzzammil 73:9, Ma’arij 70:40)

7 Annual Motion of the Sun, Moon, Planets & Stars (Q. 55:17)
SUMMER SOLSTICE EQUINOXES WINTER SOLSTICE N E N S W Easts (Multiple, Two limits) Wests (Multiple, Two limits)

8 The Moon - Basic Facts The Earth travels around the Sun once every 365 days (& 6 hours) The Moon travels around the Earth once every 29 ½ days A lunar year of 12 lunar months has 354 days Phases of the moon result from parts of the Moon reflecting the Sun’s light towards the Earth A lunar month has either 29 or 30 days (hadith)

9 Phases of the Moon

10 Looking for the New Crescent
Only visible after sunset Must wait for the sun’s glare to die down Experience shows that the best time to see the crescent is about 20 minutes after sunset (when the sun is 5° below horizon) Perfect timing if the Sunnah is followed (Salat al-Maghrib should be fairly short) Look at the western horizon, near where the sun set

11 A Good Test of Moonsighting
“When the crescent moon is visible somewhere on earth, it must be visible at all points west of it [on the same latitude] with a clear horizon.” This simple principle is also agreed by the scholars of Islamic Law, e.g. the Shafi’is, Ibn Taymiyyah, etc.

12 ‘Id al-Fitr Hilal, Shawwal 1425 (Brunei)

13 Moonsighting - History
The Islamic calendar is a purely lunar one Islam abolished the Pre-Islamic Arabian method of intercalation Until relatively recently, the start of each lunar month was determined purely by observation of the new crescent moon If cloudy, use a simple alternating 29/30 day rule Communication constraints meant there was no controversy across the vast Muslim lands

14 Moonsighting – Islamic Law (1)
The Shari’ah (Sacred Law) covers all areas of life Basic rule: crescent-sighting establishes the new month Calculations: controversial; different views Cannot be used to determine new month Can be used to reject false crescent-sightings Can be used to determine new month

15 Moonsighting – Islamic Law (2)
Applicability of a valid crescent-sighting One view: ikhtilaf al-matali’ (“multiple horizons”) Crescent-sighting applies only “locally” Nowadays: each state has its own horizon Another view: ittihad al-matali’ (“unified horizons”) A single sighting applies for the whole (Muslim) world

16 Views of Ibn Taymiyyah (8th/14th C)
Hilal-sighting depends on how easterly or westerly the location is, so if the hilal is seen in the east, it must be seen in the west, but not vice-versa. This is because sunset occurs later as we move further west. If the hilal has been seen in a particular location, its illumination and distance from the sun and its rays will increase at sunset to the west, and will therefore be more easily visible. The reverse case does not apply, i.e. if the hilal is seen in the westerly location, since a factor in its visibility may have been the later sunset there, such that the hilal’s distance from the sun and illumination will have increased, whereas it was closer to the sun in the easterly location.

17 Views of Ibn Taymiyyah - 2
The fixed rule (dabit) here is that this matter depends upon information, due to his saying, “Fast upon its sighting.” Therefore, whoever is informed that the hilal has been sighted, Ramadan has conclusively begun for him, with no consideration at all given to distance (i.e. no matter how near or far he is from the place of sighting). This corresponds to Ibn ‘Abdul Barr’s statement that there is no effect of news reaching built-up areas after the month is over, unlike places where news arrives during the month, where it may have an impact.

18 Views of Ibn Taymiyyah - 3
He made the hilals markers of time for the people: they cannot be so unless they are observed via sight and the news transmitted via hearing. If there is no observation, there is no marking of time, so they are not hilals. This is the most that can be established via the senses, since to specify the location where the hilal first appears by way of calculation is not correct in the least, and I have written something about that. [NO LONGER TRUE] This matter depends on the latter also, for it is not within human capability to determine specific times and locations for seeing the hilal. [NO LONGER TRUE] People can only be sure about what they see with their eyes or hear with their ears. Since the obligation upon the person who sees the hilal is to follow his sighting, and upon the person who does not see it is to follow the news that he hears, someone who neither sees nor hears anything has not achieved ihlal. Majmu’ Fatawa Ibn Taymiyyah, vol. 25, pp

19 Background - Calculations
Accurate calculations for the position of the moon have been around for thousands of years E.g. solar and lunar eclipses However, calculation of the visibility of the new crescent moon has only become significantly accurate over the last ~20 years Yallop, Ilyas, etc. Usually, the moon needs to be hours old before the crescent is visible Using conjunction (“astronomical birth”) means the month will start one day too early

20 Calculating Crescent Visibility
Simple prediction rules have existed for millenia (ancient Babylon, Greece, classical Islam, e.g. al-Bayruni, etc.) Modern criteria have been developed by: Bernard Yallop (ex-director of the Royal Observatory Greenwich) Mohammad Ilyas (Malaysia) Schaefer (kept the details secret) Odeh (Jordanian Astronomical Society)

21 Calculating Crescent Visibility (2) is based on Yallop/Ilyas and uses five factors only: The angle between Sun and Moon The (angular) height of the Moon above the horizon Earth-Moon distance Earth-Sun distance A measure of pollution in the atmosphere’s predictions have proved accurate every month since 1994!

22 Crescent Visibility Curve – Tues 11 Sept 2007

23 Crescent Visibility Curve – Wed 12 Sept 2007 (eve of Ramadan 1428)

24 Crescent Visibility Curve – Thurs 13 Sept 2007

25 Combining Shari’ah & Science
Accept local sightings, as well as those from the East of your location, but not West. (Simple physics) Instantaneous telecommunications must be taken into account. (Ibn Taymiyyah: the matter depends on information) Calculations are now precise enough to decide Islamic lunar months, unlike in the time of mediaeval, classical scholars

26 Towards a Unified Lunar Calendar
With accurate calculations of crescent-visibility, a worldwide lunar calendar is now possible There are 3 major possibilities: Use the visibility curve as an ILDL Fix everything wrt one place, e.g. Mecca Compromise: the Unified Hejra Calendar (divide the world into three time zones)

27 Proposal 1: Crescent-Visibility curve as ILDL (International Lunar Date-Line)
30 Shawwal 1426 1 Dhul Qa’dah 1426

28 Proposal 2: Fix everything wrt one place, e.g. Makkah
30 Shawwal 1426 Makkah 1 Dhul Qa’dah 1426

29 Proposal 3: the Unified Hejra Calendar (
Western Region Central Region Eastern Region

30 Proposal 3: the Unified Hejra Calendar (
Western Region Central Region Eastern Region For Dhul Qa’dah 1426, ILDL coincides with the Solar dateline

31 The MOONWATCH Project Launched 1st Oct & will run for several years ( A mass-experiment for the UK public Part of Einstein Year (2005 is 100 years since the publication of Relativity theory) Everyone is encouraged to look for the new crescent every month and report their observations via the above website Will help improve HM Nautical Almanac Office’s crescent-visibility calculations, in sha’ Allah

32 The MOONWATCH Project Since October 2005 (Ramadan 1426), about 3000 observations of the hilal, both positive and negative, have been reported to the Moonwatch website from around the world ALL the results are, so far, consistent with the current Greenwich model for predicting the visibility of the hilal

33 Links
UK_Islamic_Astronomy yahoogroup (Jordanian Astronomical Society) (Islamic Crescent Observation Project)

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